Have you ever wondered why eating hot food makes you sweat? I have wondered, but until yesterday, I knew only that there was a relationship between the amount of capsaicin in a the ingredients of a dish and sweating. I did not know the nature of that relationship. Yesterday, I made a point of learning a bit more about the subject. What I found was fascinating.
A protein known as the transient receptor potential cation channel subfamily V member 1 (TRPV1) functions to detect and regulate body temperatures in humans. This protein, according to some of the literature I read, is encoded in the TRPV1 gene. TRPV1 is activated by high temperatures (greater than 109°F), as well as by capsaicin (which is found in varying degrees in chiles) and by allyl isothiocynate (an organosulfur that provides the pungency for mustard and wasabi).
According to one article:
Capsaicin, the main pungent ingredient in hot chili peppers, elicits a sensation of burning pain by selectively activating sensory neurons that convey information about noxious stimuli to the central nervous system. The protein encoded by this gene is a receptor for capsaicin and is a non-selective cation channel that is structurally related to members of the TRP family of ion channels. This receptor is also activated by increases in temperature in the noxious range, suggesting that it functions as a transducer of painful thermal stimuli in vivo.
Simply put, if I correctly understand what I read yesterday afternoon, consuming foods with capsaicin triggers the protein to react, effectively tricking the body to behave in a way consistent with attempting to cool itself down (by sweating). In addition, capsaicin causes the protein to trigger the body to react otherwise as it would to high heat, i.e., to feel pain. Hence the pain on the tongue or eyes or even the skin when in contact with capsaicin. The more capsaicin, the more pain. Up to a point.
Some research suggests that long exposure to capsaicin desensitizes the body to the triggers, enabling one to tolerate greater exposure of higher amounts. And some even suggest that external applications of capsaicin can aid in the reduction of pain for things like arthritis. In fact I have a tube of cream, containing capsaicin, that claims to do that; I once applied it liberally to my elbows, thinking I was using a tube of cortisone cream. My hands got red and painfully hot for hours.
Anyway, I now have a better understanding of why I sweat when I eat the food I cook. I typically use plenty of capsaicin. I must have ample supplies of TRPV1 in my body. That helps the chiles I use make me hurt (and sweat) so good.